User`s manual

Ewave Stamper User’s Manual V1.0

6 Using the STAMPER as a General Purpose Data Link

6.1 Introduction

It is extremely easy to use the STAMPER modems to send serial data wirelessly between a BASIC Stamp

and any other serial device such as a PC, another BASIC Stamp, or any other device with a serial port.

The STAMPERS are designed to look like a wired connection to your application. They provide a by-

directional full duplex wireless link.

When first powered-up the STAMPERs automatically establish a radio link. Any serial data that the

STAMPER receives on its serial input line is packetized and transmitted to the other STAMPER via radio

waves. The second STAMPER receives the radio data packet and then transfers the data via its serial

output line to the attached device.

Your application does not need to send any set up or configuration commands to the modem. The

STAMPER communicates at 9600 baud. Your application needs to be at 9600 baud to communicate

correctly with the STAMPERs. If you have an application that requires a different baud rate, consult the

Ewave Radio Modem Technical Manual at http://www.electrowave.com for similar wireless link products

that support other baud rates.

Using the standard 9600 baud rate is recommended, and unless the application absolutely requires an other

rate, it is suggested that this be used as the default.

6.2 Supplying Power to the STAMPER Modem

The STAMPER may be powered through the external 2.1 mm power jack with 7.2-10Volts using the

supplied AC adapters, or they may be powered through the 9 pin serial connector. If powering through the

serial connector, the user may either supply unregulated 7.2-10 Volts to pin 9, or regulated 5 volts to pin 6.

It should be noted that when the STAMPER is powered with 7.2-10 Volts, then 5 volts, 40 milliamperes

regulated power is available to the user on pin 6 to power external devices, such as a BASIC Stamp board.

Consult the Ewave Radio Modem Technical Manual for additional details.

6.3 Electrical Connection to the STAMPER Modem’s Data Port

The STAMPER modem is designed to simplify wireless data communication as much as possible. Only

three lines need to be connected between your BASIC Stamp and the STAMPER modem: Serial In (RX),

Serial Out (TX), and Ground. There are two other hardware lines available to the user: RTS, which is an

input to the modem, and CTS which is an output. These signals are not required for serial communication

and are not discussed here. A complete description of the optional functions of RTS and CTS may be

found in the Ewave Radio Modem Technical Manual.

The STAMPER’s serial port is designed to operate at standard RS232 voltage levels (+/- 10V typical). The

RS232 chip set used in the STAMPER also supports 0 to 5 volt input signals allowing direct connection

between a BASIC Stamp’s I/O pin and the serial input line (“RX Modem”, pin 3) of the STAMPER. This

is automatic, and requires no jumper settings.

The serial output line of the STAMPER, (“TX Modem”, pin 2) is driven to +/- 10 Volts, and should not be

directly connected to the 0 to 5 volt I/O line of the Stamp: Damage may occur! Please consult the Parallax

documentation for information on inexpensive RS232 level conversion circuits.